1. Field of the Invention
The present invention relates to a semiconductor device and, more particularly, to a semiconductor device having a structure wherein a plurality of semiconductor substrates are stacked.
2. Description of the Related Art
In recent years, a technique for directly bonding a plurality of different semiconductor substrates, in particular silicon semiconductor substrates, to each other in order to manufacture a multi-layered semiconductor substrate has been employed. A method of manufacturing a semiconductor device such as a diode on a dielectric film by using this technique generally comprises the following steps. More specifically, first and second silicon semiconductor substrates are prepared, then, one surface of the first semiconductor substrate is mirror-polished. As (arsenic) is ion-implanted in the mirror-polished surface and diffused to a predetermined depth, a heavily doped n.sup.+ -type diffusion layer is formed. Then, one surface of the second silicon semiconductor substrate is mirror-polished for growing a thermal oxide film thereon. Thereafter, these mirror-polished surfaces are bonded to each other in air at room temperature and annealed in an oxygen atmosphere at 1,100.degree. C. In addition, the first silicon semiconductor substrate side surface is polished to a predetermined thickness. Thereafter, predetermined operations are executed to form a heavily doped n.sup.+ -type diffusion layer for cathode electrode extraction and a heavily doped p.sup.+ -type diffusion layer for anode electrode extraction. Thereafter, anode and cathode electrodes are formed by patterning, thus manufacturing a diode.
On the other hand, during manufacture of the semiconductor device, contamination atoms are often contained in a substrate of the device. Therefore, a leak current at a p-n junction of the semiconductor device increases, and the lifetime of minority carriers is shortened, thus degrading the performance of the semiconductor device. In the semiconductor device using a multi-layered substrate, no consideration has been made to solve the above problems. Therefore, a high-performance and high-reliability semiconductor device cannot be manufactured.